COVID-19 vaccines: Get the facts

Find out about the different types of coronavirus disease 2019 (COVID-19) vaccines, how they work, the possible side effects, and the benefits for you and your family.

Getting a COVID-19 vaccine helps to keep you healthy. The vaccine protects against serious illness, the need for hospital care due to COVID-19 and death from COVID-19.

Staying up to date with the latest vaccine is most important for people at higher risk. That includes adults over age 65, those with weakened immune systems, people who are pregnant, and people with chronic conditions, such as heart disease, lung disease or obesity.

Serious side effects from the COVID-19 vaccine are extremely rare. Because of that, even healthy adults benefit from the COVID-19 vaccine which lowers the risk of serious illness at a similar rate to the flu vaccine.

Factors that can affect how well you're protected after a vaccine can include your age, if you've had COVID-19 before or if you have medical conditions such as cancer.

How well a COVID-19 vaccine protects you also depends on timing, such as when you got the shot. And your level of protection depends on how the virus that causes COVID-19 changes and what variants the vaccine protects against.

Talk to your healthcare team about how you can stay up to date with COVID-19 vaccines.

Yes. Catching the virus that causes COVID-19 or getting a COVID-19 vaccination gives you protection, also called immunity, from the virus. But over time, that protection seems to fade. The COVID-19 vaccine can boost your body's protection.

Also, the virus that causes COVID-19 can change, also called mutate. Vaccination with the most up-to-date variant that is spreading or expected to spread helps keep you from getting sick again.

Researchers continue to study what happens when someone has COVID-19 a second time. Later infections are generally milder than the first infection. But severe illness can still happen. Serious illness is more likely among people older than age 65, people with more than four medical conditions and people with weakened immune systems.

The 2025-2026 COVID-19 vaccines available in the United States include Moderna, Pfizer-BioNTech and Novavax. The vaccines are all approved for people age 65 and older. Each vaccine also is approved for younger people with a health condition that raises the risk of serious COVID-19 illness.

Moderna COVID-19 vaccine 2025-2026 formulas:

• Spikevax. This vaccine is approved for all people age 65 and older and for people ages 6 months to 64 years with a risk of serious COVID-19 illness.
• Mnexspike. This vaccine is approved for all people age 65 and older and for people ages 12 to 64 years with a risk of serious COVID-19 illness.

Pfizer BioNTech COVID-19 vaccine 2025-2026 formula:

• Comirnaty. This vaccine is approved for all people age 65 and older and for people ages 5 to 64 years with a risk of serious COVID-19 illness.

Novavax COVID-19 vaccine 2025-2026 formula:

• Nuvaxovid. This vaccine is approved for all people age 65 and older and for people ages 12 to 64 years with a risk of serious COVID-19 illness.

Updates to COVID-19 vaccines

In May 2025 the FDA recommended that COVID-19 vaccine updates to target a strain of the COVID-19 virus called JN.1 or a strain called LP.8.1.

The Pfizer-BioNTech and Moderna COVID-19 vaccines for 2025-2026 focus on building protection against the LP.8.1 virus strain. The Novavax COVID-19 vaccine helps build protection against the JN.1 strain.

COVID-19 vaccines help the body get ready to clear out infection with the virus that causes COVID-19.

The Pfizer-BioNTech and the Moderna COVID-19 vaccines use messenger RNA, also called mRNA. Researchers have been studying mRNA vaccines for decades.

This type of vaccine gives your cells instructions for how to make the S protein found on the surface of the COVID-19 virus.

The vaccine shot sends the mRNA into the muscle. Your muscle cells may take in the mRNA and make the S protein. Or the mRNA may be picked up by an immune cell. Either the mRNA or the S protein alerts the body to the risk of the virus. Then the body begins to create a response to prevent you from getting sick from the infection.

The Novavax COVID-19 adjuvanted vaccine is a protein subunit vaccine. These vaccines include only protein pieces of a virus that cause your immune system to react the most. The Novavax COVID-19 vaccine also has an ingredient called an adjuvant that helps raise your immune system response.

With a protein subunit vaccine, the body reacts to the proteins and creates antibodies and defensive white blood cells. If you later become infected with the COVID-19 virus, the antibodies will fight the virus. Protein subunit COVID-19 vaccines don't use any live virus and can't cause you to become infected with the COVID-19 virus. The protein pieces also don't enter the nucleus of your cells, where your DNA is kept.

No. The COVID-19 vaccines available in the U.S. don't use the live virus that causes COVID-19. Because of this, the COVID-19 vaccines can't cause you to become sick with COVID-19.

It can take a few weeks for your body to build immunity after getting a COVID-19 vaccination. As a result, it's possible that you could become infected with the virus that causes COVID-19 just before or after being vaccinated.

Some people have no side effects from the COVID-19 vaccine. For those who get them, most side effects go away in a few days.

A COVID-19 vaccine can cause mild side effects after the first or second dose. Pain and swelling where people got the shot is a common side effect. That area also may look reddish on white skin. Other side effects include:

• Fever or chills.
• Headache.
• Muscle pain or joint pain.
• Tiredness, called fatigue.
• Upset stomach or vomiting.
• Swollen lymph nodes.

For younger children up to age 4, symptoms may include crying or fussiness, sleepiness, loss of appetite, or, less often, a fever.

In rare cases, getting a COVID-19 vaccine can cause an allergic reaction. Symptoms of a life-threatening allergic reaction can include:

• Breathing problems.
• Fast heartbeat, dizziness or weakness.
• Swelling in the face or throat.
• Hives. Full body rash.

If you or a person you're caring for has any life-threatening symptoms, get emergency care.

Less serious allergic reactions include a general rash other than where you got the vaccine, or swelling of the lips, face or skin other than where you got the shot. Contact your healthcare professional if you have any of these symptoms.

You may be asked to stay where you got the vaccine for about 15 minutes after the shot. This allows the healthcare team to help you if you have an allergic reaction. The healthcare team may ask you to wait for longer if you had an allergic reaction from a previous shot that wasn't serious.

Contact a healthcare professional if the area where you got the shot gets worse after 24 hours. And if you're worried about any side effects, contact your healthcare team.

The vaccines that help protect against COVID-19 are safe and effective. Clinical trials tested the vaccines to make sure of those facts. Healthcare professionals, researchers and health agencies continue to watch for rare side effects, even after hundreds of millions of doses have been given in the United States.

Side effects that don't go away after a few days are thought of as long term. Vaccines rarely cause any long-term side effects.

If you're concerned about side effects, safety data on COVID-19 vaccines is reported to a national program called the Vaccine Adverse Event Reporting System in the U.S. This data is available to the public. The U.S. Centers for Disease Control and Protection (CDC) also has created v-safe, a smartphone-based tool that allows users to report COVID-19 vaccine side effects.

If you have other questions or concerns about your symptoms, talk to your healthcare professional.

In some people, COVID-19 vaccines can lead to heart complications called myocarditis and pericarditis. Myocarditis is the swelling, also called inflammation, of the heart muscle. Pericarditis is the swelling, also called inflammation, of the lining outside the heart.

Symptoms to watch for include:

• Chest pain.
• Shortness of breath.
• Feelings of having a fast-beating, fluttering or pounding heart.

If you or your child has any of these symptoms within a week of getting a COVID-19 vaccine, seek medical care.

The risk of myocarditis or pericarditis after a COVID-19 vaccine is rare. These conditions have been reported after COVID-19 vaccination with any of the vaccines offered in the United States. Most cases have been reported in males ages 12 to 39.

These conditions happened more often after the second dose of the COVID-19 vaccine and typically within one week of COVID-19 vaccination. Most of the people who got care felt better after receiving medicine and resting.

These complications are rare and also may happen after getting sick with the virus that causes COVID-19. In general, research on the effects of the most used COVID-19 vaccines in the United States suggests the vaccines lower the risk of complications such as blood clots or other types of damage to the heart.

If you have concerns, your healthcare professional can help you review the risks and benefits based on your health condition.

Talk to your local health department, pharmacy or a health professional for information on where you can get a COVID-19 vaccine. In the U.S., COVID-19 vaccines may be offered at no cost through insurance coverage. For people whose vaccines aren't covered or for those who don't have health insurance, options are available. Anyone younger than 18 years old can get no-cost vaccines through the Vaccines for Children program.

Yes, COVID-19 vaccines are safe for people who have existing health conditions, including conditions that have a higher risk of getting serious illness with COVID-19.

The COVID-19 vaccine can lower the risk of death or serious illness caused by COVID-19. Your healthcare team may suggest that you get added doses of a COVID-19 vaccine if you have a moderately or severely weakened immune system.

Cancer treatments and other therapies that affect some immune cells also may affect your COVID-19 vaccine. Talk to your healthcare professional about timing additional shots and getting vaccinated after immunosuppressive treatment.

Talk to your healthcare team if you have any questions about when to get a COVID-19 vaccine.

Don't take medicine before getting a COVID-19 vaccine to prevent possible discomfort. It's not clear how these medicines might impact the effectiveness of the vaccines. It is OK to take this kind of medicine after getting a COVID-19 vaccine, as long as you have no other medical reason that would prevent you from taking it.

Symptoms of a life-threatening allergic reaction can include:

• Breathing problems.
• Fast heartbeat, dizziness or weakness.
• Swelling in the throat.
• Hives.

If you or a person you're caring for has any life-threatening symptoms, get emergency care right away.

Less serious allergic reactions include a general rash other than where you got the vaccine, or swelling of the lips, face or skin other than where the shot was given. Contact your healthcare professional if you have any of these symptoms.

Tell your healthcare professional about your reaction, even if it went away on its own or you didn't get emergency care.

If you had an immediate, serious allergic reaction to a COVID-19 vaccine or any ingredient in the vaccine, do not get another COVID-19 shot.

If you've had an allergic reaction to other vaccines, you may be able to get the COVID-19 vaccine. But you'll need to stay where you got the shot for at a time, often 30 minutes. That allows the healthcare team to make sure you won't have a serious reaction.

If you had a reaction but it wasn't life threatening, such as hives or swelling in places other than the airway, you may be able to get a COVID-19 vaccine. But talk with a healthcare professional about what's safe for you.

Yes, getting a COVID-19 vaccine protects against serious illness, the need for hospital care due to COVID-19 and death from COVID-19. Staying up to date with the latest vaccine is most important for people at higher risk including people who are pregnant. If you get the vaccine during pregnancy, it may help a newborn avoid getting seriously ill with COVID-19 COVID-19 vaccines do not affect breastfeeding.

While rare, some children can become seriously ill with COVID-19 after getting the virus that causes COVID-19.

A COVID-19 vaccine helps prevent your child from getting the virus that causes COVID-19. It also may prevent your child from becoming seriously ill or having to stay in the hospital due to the COVID-19 virus.

Don't stop all your safety precautions after you get a COVID-19 vaccine. The steps you take to prevent COVID-19 help protect you and others from getting sick.

These steps are even more important when you're in an area with a high number of people with COVID-19 in the hospital. Protection also is important as time passes since your last vaccination.

In general, make it a habit to:

• Test for COVID-19. If you have symptoms of COVID-19 test for the illness. Or test five days after coming in contact with the virus.
• Help from afar. Avoid close contact with anyone who is sick or has symptoms, if possible.
• Wash your hands. Wash your hands well and often with soap and water for at least 20 seconds. Or use an alcohol-based hand sanitizer with at least 60% alcohol.
• Cover your coughs and sneezes. Cough or sneeze into a tissue or your elbow. Then wash your hands.
• Clean and disinfect high-touch surfaces. For example, clean doorknobs, light switches, electronics and counters regularly.

Try to spread out in crowded public areas, especially in places with poor airflow. This is important if you have a higher risk of serious illness.

Wear a mask when you're inside a crowded place with poor airflow. This is most important when many people in the area are sick with COVID-19 or the flu.

COVID-19 vaccination will protect most people from getting sick with COVID-19. But some people who are up to date with their vaccines may still get COVID-19. These are called vaccine breakthrough infections.

People with vaccine breakthrough infections can spread COVID-19 to others. However, people who are up to date with their vaccines but who have a breakthrough infection are less likely to have serious illness with COVID-19 than those who are not vaccinated. Even when people who are vaccinated get symptoms, they tend to be less severe than those felt by unvaccinated people.

Researchers continue to study what happens when someone has COVID-19 a second time. Reinfections and breakthrough infections are generally milder than the first infection. But severe illness can still happen. Serious illness is more likely among people older than age 65, people with more than four medical conditions and people with weakened immune systems.